In discing the blade angle decreases from 17.5 to a minimum of 1.5 degrees. However, there is no significant change in Tq.
The Bombardier AOM states:
"When the POWER Levers are moved aft of the FLIGHT IDLE gate in-flight, the Propeller Governor, Propeller Overspeed Governor and the BETA Backup logic protection are all inhibited
and Propeller speed control is no longer available. In this condition the propeller(s) would be
driven uncontrollably toward a Reverse pitch condition resulting in an overspeeding propeller
and substantial engine damage leading to possible engine failure."
However, if this was the case, I suspect the plane would come straight down. I've never heard of a prop overspeed of 60% due to Condition Lever(s) being moved too rapidly and I suspect if such a thing did occur, the manufacturer would send out a crew advisory.